Compile with GHC 8.8

This doesn't include the updates needed for Cabal 3.0 compatibility.

idris.cabal

@@ -100,7 +100,7 @@ source-repository head
 
 custom-setup
   setup-depends:
-    Cabal >= 1.10 && <2.5,
+    Cabal >= 1.10 && < 3.1,
     base  >= 4 && <5,
     directory,
     filepath,
@@ -292,16 +292,16 @@ Library
                 , megaparsec >= 7.0.4 && < 8
                 , mtl >= 2.1 && < 2.3
                 , network >= 2.7 && < 2.9
-                , optparse-applicative >= 0.13 && < 0.15
+                , optparse-applicative >= 0.13 && < 0.16
                 , parser-combinators >= 1.0.0
                 , pretty < 1.2
                 , process < 1.7
                 , regex-tdfa >= 1.2
                 , safe >= 0.3.9
                 , split < 0.3
                 , terminal-size < 0.4
-                , text >=1.2.1.0 && < 1.3
-                , time >= 1.4 && < 1.9
+                , text >=1.2.1.0 && < 1.4
+                , time >= 1.4 && < 2.0
                 , transformers >= 0.5 && < 0.6
                 , uniplate >=1.6 && < 1.7
                 , unordered-containers < 0.3
@@ -314,6 +314,7 @@ Library
 
   if !impl(ghc >= 8.0)
     Build-Depends: semigroups == 0.18.*
+                , fail == 4.9.0.*
 
   Default-Language: Haskell2010
   ghc-prof-options: -auto-all -caf-all

src/Idris/CmdOptions.hs

@@ -18,6 +18,7 @@ import Idris.Info (getIdrisVersion)
 import Idris.Options
 import IRTS.CodegenCommon
 
+import qualified Control.Monad.Fail as Fail
 import Control.Monad.Trans (lift)
 import Control.Monad.Trans.Except (throwE)
 import Control.Monad.Trans.Reader (ask)
@@ -264,7 +265,7 @@ parseCodegen :: String -> Codegen
 parseCodegen "bytecode" = Bytecode
 parseCodegen cg         = Via IBCFormat (map toLower cg)
 
-parseLogCats :: Monad m => String -> m [LogCat]
+parseLogCats :: Fail.MonadFail m => String -> m [LogCat]
 parseLogCats s =
     case lastMay (readP_to_S doParse s) of
       Just (xs, _) -> return xs
@@ -290,7 +291,7 @@ parseLogCats s =
       s <- look
       fail $ "Category: " ++ s ++ " is not recognised."
 
-parseConsoleWidth :: Monad m => String -> m ConsoleWidth
+parseConsoleWidth :: Fail.MonadFail m => String -> m ConsoleWidth
 parseConsoleWidth "auto"     = return AutomaticWidth
 parseConsoleWidth "infinite" = return InfinitelyWide
 parseConsoleWidth  s =

src/Idris/Core/CaseTree.hs

@@ -627,7 +627,7 @@ groupCons cs = gc [] cs
         PConst cval -> return $ addConG cval (ps, res) acc
         PSuc n -> return $ addg False CSuc [n] (ps, res) acc
         PReflected fn args -> return $ addg False (CFn fn) args (ps, res) acc
-        pat -> fail $ show pat ++ " is not a constructor or constant (can't happen)"
+        pat -> error $ show pat ++ " is not a constructor or constant (can't happen)"
 
     addg uniq c conargs res []
            = [ConGroup uniq c [(conargs, res)]]

src/Idris/Core/TT.hs

@@ -70,6 +70,7 @@ import qualified Prelude as S (Semigroup(..))
 import Control.Applicative (Alternative, Applicative(..))
 import qualified Control.Applicative as A (Alternative(..))
 import Control.DeepSeq (($!!))
+import qualified Control.Monad.Fail as Fail
 import Control.Monad.State.Strict
 import Data.Binary hiding (get, put)
 import Data.Char
@@ -324,6 +325,11 @@ bindTC x k = case x of
 instance Monad TC where
     return x = OK x
     x >>= k = bindTC x k
+#if !(MIN_VERSION_base(4,12,0))
+    fail = Fail.fail
+#endif
+
+instance Fail.MonadFail TC where
     fail e = Error (InternalMsg e)
 
 instance MonadPlus TC where

src/Idris/Parser/Stack.hs

@@ -36,6 +36,7 @@ import Idris.Core.TT (FC(..))
 import Idris.Output (Message(..))
 
 import Control.Arrow (app)
+import qualified Control.Monad.Fail as Fail
 import Control.Monad.State.Strict (StateT(..), evalStateT)
 import Control.Monad.Writer.Strict (MonadWriter(..), WriterT(..), listen,
                                     runWriterT, tell)
@@ -51,7 +52,7 @@ import qualified Util.Pretty as PP
 type Parser s = StateT s (WriterT FC (P.Parsec Void String))
 
 -- | A constraint for parsing without state
-type Parsing m = (P.MonadParsec Void String m, MonadWriter FC m)
+type Parsing m = (Fail.MonadFail m, P.MonadParsec Void String m, MonadWriter FC m)
 
 -- | Run the Idris parser stack
 runparser :: Parser st res -> st -> String -> String -> Either ParseError res